This invention relates to a process for the production of ethylene oxide by oxidizing ethylene, and to a catalyst therefor. It is based on the new discovery that a combination of sodium, cesium and bromine and/or fluorine with silver provides a catalyst having increased performance in the oxidation of ethylene. Bromine and/or fluorine will be referred to as "halogen" hereinafter.
A silver catalyst is substantially the sole catalyst component used in the industrial production of ethylene oxide by the oxidation of ethylene with molecular oxygen. Silver alone, however, did not prove to be a perfect industrial catalyst, and efforts have been made to increase its performance by including various additives (for example, U.S. Pat. Nos. 2,238,471, 2,404,438, 2,671,764 and 2,799,687). Many of these efforts have been directed to the addition of alkali metals (for example, British Pat. No. 1,413,251 and U.S. Pat. No. 4,212,772). Usually, halogen compounds of these metals are excluded because they are a poison to silver.
The present invention have made extensive investigations about the effects of anionic components as well as alkali metals as cationic components. These investigations have led to the discovery that the use of the aforesaid specified halogen elements (to be referred to simply as a halogen element), previously believed to have a poisonous action, in combination with sodium and cesium unexpectedly gives a catalyst having greatly increased performance.